Parallel Syntactic Processing in the Flankers Task: Insights From ERP Decoding

The current paper reports the results of two ERP experiments that investigated the extent to which syntactic information can be extracted from the parafovea. We used the reading version of the flankers task in which participants had to classify foveal target words as either being a noun or an adjective. In Experiment 1, targets were flanked by either syntactically congruent or incongruent words (e.g., noun noun noun vs. adjective noun adjective), or were embedded in a sequence of words that was either grammatical or ungrammatical (e.g., adjective noun verb vs. verb noun adjective). Experiment 2 employed the same stimuli as the latter condition, with participants now tasked to judge the word sequence as being grammatically correct or not. Results showed a significant reduction in N400 amplitude for both the syntactically congruent and syntactically grammatical conditions in Experiment 1, and for syntactic grammaticality when making sentence judgments in Experiment 2. In the second experiment, a syntactically grammatical word sequence could be reliably decoded starting around 500 ms post-stimulus onset. These results indicate that skilled readers can extract and process syntactic information from multiple words in a short timeframe and that syntactic categories retrieved from individual words (i.e., parts-of-speech) are rapidly integrated into a sentence-level representation.